Planoorapif co



1. e. HOOPER AND F. R. HOBLEY.

ELECTRICAL INDICATOR AND LIKE APPARATUS. APPLICATION FILEDJUNE 5. ma.

A 1,308,590. Patented July 1, 1919.

2 SHEETS-SHEET 1. G. HOOPER AND F. R.-HOBLEY.

ELECTRICAL INDICATOR AND LIKE APPARATUS.

APPLICATION HLED JUNE 5.1918.

Patented J ulj 1, 1919.

2 SHEETS-SHEET 2.

Wiinfisses UNITED STATES PATENT OFFICE.

JAMES GEORGE HOOPER AND FREDERICK RICHARD HOBLEY, 0F VAN, NEAR LLANIDLOES, WALES. I

ELECTRICAL INDICATOR AND LIKE APPARATUS.

Application filed .Tune 5, 1918.

To all whom it may concern.

Be it known that we, JAMES Gnonon Hoornn and FREDERICK RICHARD HOBLEY, subjects of the King of England, and both residents of Van, near Llanidloes, in the county of Montgomery, ales, have invent-,

ed certain new and useful Improvements in Electrical Indicators and like Apparatus, of which the following is a specification.

This invention relates to electrical indicating apparatus of the known type for the transmission of orders and like signals in which a rotary-field device is employed as the indicator and has the junction points of its coils connected to tappings on a controller circuit that is closed and that is provided with a switch by whose means an electromotive force is applied across two selectively adjustable points in the said closed circuit. It has been proposedto use this type of apparatus for the transmission of order signals, but we have found difliculty in so constructing it as to give very fine indications.

The present invention provides indicating apparatus of the type defined, wherein the motor-portion of the indicator comprises coils connected together as in a three-phase rotary field system and mounted on a nonmagnetic support to rotate in a magnetic field; a nonmagnetic support is selected in order to avoid the effect of hysteresis upon the indications.

According to another feature the controller circuit is arranged as two lengths of resistances extending side by side with one another and having their four extreme ends cross-connected, the far end of one to the near end of the other, and the controller switch is movable along the said lengths to apply the electromotive force across a point on one and a point on the other just opposite to the first.

y way of more clearly indicating the nature of this invention, it is hereinafter described by reference to the accompanying drawings, in which Figure 1 is a typical diagram of the electrical circuits of the apparatus;

Fi 2 is a dia ram of an alternative arb b rangement;

F1 3 1s a ers ectiveview of a con- 6 troller;

Fig. 4: is a perspective view of an indicator, constructed according to this inven- Specification of LettersPatent.

'with a controller switch wound with a simple 3-phase indicate its direction.

Patented July 1, 1919. Serial No. 238,409.

illOl, controlled by the controller of Fig. 3, an

Fig. 5 is a diagram of a modified arrangement of electrical circuits.

The diagram of Fig. 1 shows the known arrangement of a controller circuit A in the form of a circular resistance circuit, closed upon itself to constitute an annulus, B rotatable about the center of the annulus to make sliding contact by its two contacts B B with the annulus at opposite ends of a diameter thereof.

Slip rings B B are provided, and the contact B is connected to the ring 13,, and the contact B to the ring 13 by brushes;

the contacts B B are insulated from one whose coils are indicated at G G G The device is diagrammatically shown as meshwound; it may equally well be star-wound or otherwise wound provided it affords three points that are electrically and electromagnetically symmetrical. Thus, if it is three-coil star winding, the three free ends of the coils will clearly be the points to be connected one to each tapping T T T, described below. The coils G G G3 combine to produce a resultant field whose direction is determined by the angular position of the switch B about its center of rotation. Consequently, rotation "of the switch causes rotation of the field, and any device whose position can be controlled by the direction of the resultant field of G G ,v G is added, so as to be subjected to that field and to Such a device is indicated in diagram by a pivoted magnet g. In practice, however, the moving element must not contain magnetic material. This constitutes the indicator member of the indicator formed by the parts G G, G, and g, and always takes a position about its pivot, determined by the position of the switch B about its pivot.

A modified construction of, controller a, are cross-connected as shown. These are bridged by a switch-arm Z) making sliding contact at its ends with the twolengths a, a and applying to them at the contact points theelectromotive force of a battery diagrammatically shown as carried upon the arm 6. Electrically equidistant tappings T T T are taken from the lengths a. a, the tapping T, coinciding with the end a of one length, and the three tappings are connected to the three terminalsof a rotary-field device '9 In this construction the switch-arm has a limited rectilinear movement as contrasted with the unlimited circular movement of the switch of Fig. 1. The indication, however, is by angular movement of the indicator member of the device 9 The apparatus .hown in Fig. 3 comprises a controlling sleeve A, rotatable about a center pillar A on a base A Upon the sleeve A, is mounted a disk E constituting primarily a switch-arm from which two .extensions E E ext-end downwardly to provide a switching action hereinafter described. On the base A, are two contact rings E E and around its outer edge are three concentric rings of contact studs F F F the members of one ring being staggered relatively to those of its next outer neighbor so that a stud on the innermost ring is intermediate, circumferentially, between one on the middle and one on the outermost rings. The extension E carries a brush at its inner-heel bearing constantly upon the ring E and three brushes at its outer end bearing on the three rings of studs F F F the arrangement of these studs and the brushes on the extension E is such, however, that the latter only makes conducting contact with one stud at a time except momentarily in passing from one to the other. This arrangement in cooperation with the staggered order of the studs gives a finely sub-divided gradation of the point of contact of the arm E, with the studs F F F The extension E has a similar construction with a brush at its inner heel bearing on the ring E and three brushes at its outer end bearing on the contacts F F F The extensions E, E, are also conductingly connected by wires supported on the sleeve A, to any desired apparatus also carried by the sleeve A,, but not forming part of the present invention.

A battery is permanently connected across the rings E E I Between the studs F F F are connected resistances, all equal to one another, so that these three concentric rings of studs provide the electrical equivalent of the annulus A of Fig. 1; that'is herein called the resistance F. V r r nagnet K on a vertical spindle J magnet The indicator is shown in Fig. at and comprises a drum J of non-magnetic material, a. g, aluminium, provided with three pancake coils, of which one only, J is marked in the drawing, he coils being mounted to revolve within the embrace of a permanent about the axis P -P and constituting with the K a rotary field device.

It will be observed that the rotating portion of this indicator is entirely constructed of non-magnetic material at least where it 1 lies within the sphere of the magnetic field,

sothat there is no efiect of hysteresis upon the moving parts. This is or great importance where fine and accurate indications are required, such for example as indications within one degree of arc in a rotary apparatus. The particular piece of mechanism comprising the indicator is selected by this invention for application to indicating apparatus of the kind defined in order that such an apparatus may give superior results to those hitherto obtained, the said superiority being in fineness of indication and in accuracy in spite of reversals of movement. In short, the selection of the said known construction avoids the occurrence of those errors in the indications which result from hysteresis in the moving parts.

Three slip rings and brushes N N, serve to convey current to the moving coils upon the drum J. Suitable terminals for these various brushes are provided on a base- 0 supporting the indicator. Any desired device, such for example as a pointer, may be mounted on the spindle J The connections between the controller and indicator are illustrated in Fig. 1 where the annulus-A and thecoils G G G correspondrespectively with the resistance ring F and the coils J, on the drum J. The battery is indicated at B in Fig. 1 and it will readily be understood from the foregoing description that this battery serves to apply a voltage constantly to the rings E E This voltage is then applied by the switch-arms E, to the resistance F at points that are selectively adjustable and determined by the position of the sleeve A about the axis A The voltage need not be of constant value; variations in its magnitude do not vary the indications of the indicator.

The electromoti ve force thus applied to the two selected points on the resistance ring is transmitted from the three tapping points to the three junction points of the coils on'the rotary-field device so that the drum J receives a. movement of rotation mitil it takes up a position corresponding with the angular position of thearms E, E V The arrangement shown in Fig. 2 offers a construction which allows the switch to have a movement of translation instead of oneof rotation. Alternatively, the ends of the lengths or a may be connected a to a, and a, to a, instead of being cross-connected and two contact makers arranged, one for each length, so connected together that as one moves in one direction the other moves in the opposite direction, to apply the electromotive force of the battery across two points so that the resistance through the controller circuit from one of these contacts to the other has always the same value.

Obviously, instead of the battery B any direct current electrical generator may be employed, and the whole apparatus may be made large and powerful so that the indicator member exemplified at g is operated by large forces.

Where it is desired to give to the indicator-member a movement having a less simple relation to the movement of the switch than that obtained by a uniform resistance gradient, the resistance of the controllercircuit may be correspondingly varied from point to point to give the required gradient. Alternatively the desired result may be obtained by inserting a resistance, which will be termed a corrector, in one or more of the leads connecting the indicator memher to the tappings on the controller circuit. Such an arrangement is exemplified diagrammatically in Fig. 5. In this figure it will be seen that a corrector a is mounted by the side of the controller resistance a; a and the switch 6 is provided with an extension b, which makes sliding connection with the corrector a The contact-piece of the extension 6 is insulated from the rest of the switch and is connected by a flexible connection 9 to one terminal of the indicator member and one end of the corrector is connected to the point T of the controller circuit. This said terminal of the indicator member therefore is connected to the tapping point T through a portion of the corrector a, the amount of which portion is determined by the position of the switch 6. If desired the corrector a, may be mounted on a base movable relatively to the 0011- troller circuit a a in the direction of the path of the switch; such a mounting is indicated in Fig. 5. By this means, as will readily be understood, the precise effect of the corrector may be adjustably varied because the amount of resistance a included at any given position of the switch 7) may be thus varied. In order to permit of the relative motion between the corrector and the controller circuit the connection between the two is effected by a flexible connection 9 Obviously the corrector may be inserted in any or all of the leads between the tapping points and the indicator member and the precise gradient employed in any corrector may readily be determined by those skilled in the art to give any desired correction; the gradient may be a constant,

a smoothly varying or an irregular varying one.

The resistance a, applies a modification to the indications of the indicator 9, when such modification is desired. An example of such conditions is found in transmitting instructions for the setting of gun-sights. Without the corrector resistance a, the indicator g coil-system carried upon a non-magnetic support rotatably mounted in the said magnetic field, andl circuits connecting three terminal points on the said coil-system with three tappings in the said controller circuit, substantially as set fortl.

2. In electrical indicating apparatus the combination of, a closed controller circuit, means to apply an electromotive force between two selectively adjustable points in the said controller circuit, means to produce a magnetic field, a three-phase rotary field coil-system carried upon a thin-walled hollow cylinder of non-magnetic metal rotatably mounted in the said magnetic field, and circuits connecting three terminal points on the said coil-system with three tappings in the said controller circuit, substantially as set forth.

'3. In electrical indicating apparatus the combination of, a closed controller circuit, means to apply an electromotive force between two selectively adjustable points in the said controller circuit, means to produce a magnetic field, a three-phase rotary field coil-system 'rotatably mounted in the said magnetic field, and circuits connecting three terminal points on the said coil-system with three tappings in the said controller circuit whereof one or more of the said circuits comprises a variable resistance automatically adjusted by means operatively connected with the said means electromotive force to the controller circuit, substantially as set forth.

4. In electrical indicating apparatus the combination of, a closed controller circuit composed of two substantially straight-line conductor-portions arranged side by side with their respective ends cross-connected one to the other and a switch-member movable with a movement of translation in a path substantially parallel to the said straight-line portions and connected to a for applying an source of electromotive force, means to produce a magnetic field, a three-phase rotary field coil-system rotatably mounted in the said magnetic field, circuits connecting three terminal points upon the said coil-system with three tappings upon the controller circuit of which said tappings one or more comprises a substantially straight-line conductor of graded resistance, and means operatively connected with the said means for applying an electromotive force to the controller Copies of this patent may be obtained for five cents each, by addressing the whereby the portion of the said graded resistance included in its said circuit is automatically varied, substantially as set forth. In testimony whereof We have signed our names to this specification in the presence of two subscribing Witnesses.

JAMES GEORGE HOOPER. FREDERICK RICHARD HOBLEY. Vitnesses JAMES LEWIS JONES, EVAN DAVIES.

Commissioner of Patents.

Washington, D. G. 

